For starters, you'll need to make sure it has a working 6v battery. Since this is an old camera, if there is a battery in it then it may be dead (or at least too weak to trust). You'll need film and you'll need to know how to load the film and how to set the ISO/ASA speed of the film (so that the camera will know how to indicate correct exposures for you via the light meter.) There are LOTS of film choices. You need "135" film. But it'll be called "135-24" if it has 24 exposures on the roll, or "135-36" if it has 36 exposures on the roll. You can pick B&W or color. You can pick print or slide film. You can pick films with different ISO speeds (ISO and ASA are interchangeable terms... so you may see "100 ASA" but that's the same as ISO 100.) The films all have their own character... the amount of grain, saturation, etc. Some films offer subdued and gentle color. Some offer rich intense saturated color, etc.
You'll need to know how to set the f-stop and shutter speed... or how to tell the camera to do that for you (by setting the f-stop ring to the "A" (automatic) setting and/or setting the shutter speed dial to the "Program" setting.) Focusing is pretty easy because of the split-prism focus aid in the center of the viewfinder frame.
If you don't have the manual to your camera, there are several websites that have scanned the manual to PDF so you can download it. For example:
http://jameskbeard.com/Photography/.../AE-1 Program Camera Owners Manual (1981).pdf
If you've never loaded 35mm film into a camera, you might want to watch a few YouTube videos that demonstrate the process. There's no automatic film loading feature -- you have to make sure the film leader is inserted into the take-up spool and the the "teeth" on the take up spool are really grabbing the holes on the edge of the 35mm film. Probably everyone who has ever shot enough 35mm film has, at one time or other, mis-loaded the film and shot an entire roll and upon developing it they realize the film was mis-loaded and the film wasn't REALLY advancing inside the camera (so they only *thought* they shot a roll of film.)
Here's a pretty good website dedicated to explaining how to use an AE-1 Program:
http://www.mir.com.my/rb/photography/companies/canon/fdresources/SLRs/ae1pgrm/index.htm
Shooting is typically a slower and more deliberate process with a film camera as you are learning (don't be in a hurry). Unlike a digital camera, there's NO indication of whether the shot you just took will be good. Careful checking of the exposures settings and focus prior to clicking the shutter button are the only thing you have to rely on. As you get used to checking the exposure with each shot you learn to shoot faster. Although... since this is an AE-1 Program, you can put it in fully automatic program-ae mode. As long as you correctly set the ISO dial when you loaded the film, the camera will generally either do the right thing OR it'll blink warnings through the viewfinder if the shot is going to be either over-exposed or under-exposed. But there's no auto-focus. No image stabilization. So you have to realize when the indicated "correct" exposure involves a dangerously slow shutter speed.